On Thu, 19 Mar 2009, esemba wrote:
Hi,
I have table with several columns and need to perform fulltext search over
volatile number of columns.
I can't use multicolumn gist index or gin index over concatenated columns,
so I've created several single column indexes (one for each column I want to
search) and now I need to query them like this:
to_tsvector('cs', coalesce(annotation, '')) || to_tsvector('cs',
coalesce(resume, '')) || ...
@@ to_tsquery('cs', 'Query text');
alter table YOURTABLE add columnt fts tsvector;
update YOURTABLE set fts=
to_tsvector('cs', coalesce(annotation, '')) ||
to_tsvector('cs', coalesce(resume, '')) || ...
create index fts_idx on YOURTABLE using gin(fts);
vacuum analyze YOURTABLE;
select * from YOURTABLE where to_tsquery('cs', 'Query text') @@ fts;
This query works, but EXPLAIN has shown me, that postgres doesn't use the
indexes, so the query over a table with several thousands of records last
very long time. I've figured out, that indexes probably cannot be used this
way. What is a recommendation for this scenario?
Indexes over static number of columns work fine, but I can't use them,
because in my application logic I want to let user choose which columns to
search.
Thank you for your reply.
Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@xxxxxxxxxx, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83
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